CZ20003991A3 - A method of multistage biological treatment of intermittent waste water and apparatus for performing such a method - Google Patents

Abstract

A method of multi-stage biological wastewater treatment with intermittent operation in a device consisting of at least two pre-purification reactors, a purification reactor and an internal air recirculation circuit connected to at least one source of compressed air, the essence of which is that, depending on the selected time intervals or the amount of incoming wastewater, a controlled separate purification process takes place in each of the pre-purification reactors according to preset parameters, consisting of aeration of the purified water and a selected combination of purification phases consisting of mixing of the purified water and settling of sludge, while ensuring the pumping of the pre-purified water into the purification reactor, where a complex purification process consisting of mixing and aeration of the purified water and settling of sludge simultaneously takes place in the purification reactor, while ensuring the pumping of purified water, recirculation of the return sludge back into each or some of the pre-purification reactors and with occasional pumping of excess sludge outside the device, when the start or end of the individual phases cleaning processes in pre-cleaning reactors or in the cleaning reactor are initiated based on the evaluation of level fluctuations in the cleaning reactor using float switches.

Description

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of multi-stage biological wastewater treatment with intermittent operation using an activated sludge activated sludge system and an apparatus for carrying out this method, which is particularly suitable for treating sewage from small local housing or restaurant and hotel facilities.

BACKGROUND OF THE INVENTION

Methods and devices for biological treatment of waste water are known, for example according to CZ PAT 285144 or WO 99/55628, which solve the purification process.

running with a continuous flow of purified water. In this process, in each zone of the plant, a certain stage of the purification process proceeds from coarse pre-treatment through activation in the oxide and anoxide zones to separation and settling of impurities, the entire volume of purified water being gradually pumped from zone to zone; The disadvantage of these sewage treatment plants is their relatively energetic and economical demands of operation, where the demands are on the operation and maintenance in terms of monitoring of floating impurities and concentration of activated sludge, which must be pumped out if the permitted concentration is exceeded. purified water.

Further, solutions of biological wastewater treatment with a discontinuous flow of purified water are known, for example according to the patents CZ 282411, WO 96/16908 and CZ 284697, in which, after reaching the maximum level in the activation tank or drop,

- 2 levels in the buffer tank below the minimum set level interrupt the activation process and the excess sludge and purified water are drained from the activation tank. This method of intermittent cleaning in two separate functional tanks has the disadvantage that, in the case of sudden inflows of contaminated wastewater, this very soon gets pumped incompletely into the activation tank by pumping during a short-term activation process, and thus can reach the outflow. A major problem with these devices is also the fact that in the first stages of pumping the treated water, contaminated water, which entered the pump interior during the activation phase of purification, also enters the drain. Since the excess sludge is pumped out only a few times a year, the accumulation of the sludge in the system causes a drop in oxygen levels and backwater contamination, in particular by phosphorus. A further disadvantage of these solutions is that the devices are equipped with numerous electronic controls, such as solenoid valves, and complicated interconnected control processors, which increases the likelihood of failure and shutdown of the plant.

Also known are discontinuous wastewater treatment solutions according to CZ PAT 282852 or CZ UV 4800 in a pair of separate reactors, where the individual phases of activation are continuously shortened or prolonged according to the filling and emptying of individual reactors. The disadvantage of these solutions is that when the purification process is carried out in a single reactor, sludge is produced whose properties are adapted to the particular type of waste water contamination. After the reactor has been discharged and new contaminated water of different properties has been introduced, the sludge must be adapted for a certain period of time, thereby deteriorating the purification process parameters. After the purified water is discharged, a large concentration of sludge remains in the reactor, to which new waste water is gradually admitted, resulting in an uneven biological parameters of the purification process. Another disadvantage of these solutions is the unevenness and impact rate of the outflow of purified water from the plant.

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It is also known to design a wastewater treatment plant with operation in part discontinuous and part continuous according to CZ UV 9904, whose disadvantage is the high structural complexity of the device and its control and operating elements.

3. Summary of the Invention

The above-mentioned disadvantages are largely eliminated by the intermittent operation of a multi-stage biological wastewater treatment plant in a plant comprising at least two pre-treatment reactors, a purification reactor and an internal air recirculation circuit connected to at least one compressed air source. the amount of inflow of waste water is carried out according to pre-set parameters in each of the pre-treatment reactors controlled independent cleaning process consisting of aeration of treated water and selected combination of cleaning phases consisting of mixing of treated water and sludge settling. At the same time, a complex purification process consisting of mixing and aerating the purified water and sediments takes place at the same time sewage sludge, ensuring the purging of the purified water, recirculating the return sludge back to each or any of the pre-treatment reactors, and occasionally pumping off the excess sludge outside the plant, when the healing or termination of individual stages of the purification processes in the pre-treatment reactors or purification reactor is initiated evaluation of level fluctuations in the cleaning reactor by means of float switches.

It is a further object of the invention that, upon stopping the waste water flow to the plant, compressed air is supplied intermittently to the main aerators of the pre-purification reactors and the purge reactor, by adjusting the different timing levels, thereby mixing or aerating the water without draining the purified water.

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It is also an object of the invention that when the level in the activation reactor is raised above the maximum level, the supply of pressurized air from the source to the purification reactor or to all the reactors is stopped first, and after a certain time interval At the end of the reactor, the operation of the plant is switched back to the normal mode, in which all the cleaning phases are carried out successively.

The design of the plant for carrying out the method of the invention is that the interconnected pre-treatment reactors are completely separated from the purification rector with which the last of the pre-treatment reactors is connected by a first control mammoth pump connected to the first air float armature when A coarse dirt trap is provided, wherein the activation reactor is equipped with a second booster pump for pumping clean water connected to a second float control valve, on the other hand with a first booster pump for return sludge leading to each of the pre-treatment reactors and a booster pump for excess sludge.

It is also an object of the invention that on the one hand a mammoth sludge pump is led through an aerobic excess sludge stabilizer to a sludge tank which is connected to one of the pre-treatment sludge to allow the sludge water to flow back into the purification process. a second control mammoth pump is provided, which is provided with a discharge of clean water and a second mammoth pump of the sludge return to the first pretreatment reactor.

Finally, it is an object of the invention that all mammoth pumps and reactor aerators, the post-purge stage and the surge tank stabilizer are connected to the pressurized air source via a first control element or a second control element. Advantageously, the main reactor aerators, the first air float armature and the first mammoth pump (14) of the gate are connected to one branch of the circulating air circuit coming from the first control element.

Auxiliary aerators of the pre-purification reactors are connected to the second branch, on the other hand through the second float control valve the second control mammoth pump and the second metallurgical sludge pump and the second auxiliary aerator of the excess sludge stabilizer are connected to the second control element which is connected in parallel to the second branch of the first control element, a mammoth pump of excess sludge and a first auxiliary aerator of the after-treatment stage are connected.

In an optimum embodiment, the purification reactor is provided with a first through hole for transferring the activated sludge foam to the last pre-treatment reactor, and the post-purification stage is equipped with a second through hole for transferring the activated sludge foam to the first pre-treatment reactor and equipped with a disinfectant dispenser.

According to the invention, a new and higher effect is achieved in that the purification process combines the effects of continuous and discontinuous wastewater flow through the purification plant. The cleaning process takes place automatically and evenly in each of the series-connected reactors separately, with continuous sludge recirculation between the reactors. The decomposition of the purification process into stages, where in each of the reactors a certain type of bacteria dominates the purification, results in a complex purification effect with water recovery: high purity quality. The device for carrying out the method according to the invention is relatively simple in construction, with a small number of simple controls which simplify operation and maintenance and reduce the possibility of failure and interruption of the plant operation. The device then enables economical and energy-efficient operation with automatic control of the selection of cleaning modes according to the amount of waste water inflow.

Description of the figures in the attached drawings

A specific example of the construction of the apparatus according to; The invention is schematically illustrated in the accompanying drawings, wherein FIG. 1 is a schematic block diagram of the apparatus showing the interconnection of individual components of the apparatus by means of an internal circulation circuit; FIG. 2 is a plan view of the apparatus; Fig. 4 is a vertical sectional view of the apparatus of Fig. 2 in the BB plane; and Fig. 5 is an alternative block diagram of the apparatus for large waste water treatment plants.

DETAILED DESCRIPTION OF THE INVENTION

The multi-stage wastewater treatment plant consists of two interconnected pre-treatment reactors 2, a purification reactor 3 and a post-purification stage 4, for example a settling tank, which are arranged in a common cylindrical casing 5 as shown in Figures 2 to 4. The pretreatment reactors 2 are completely separated from the purification reactor 3 when the first pretreatment reactor 21 is connected to the waste water inlet 6 and is equipped with a coarse dirt trap 1 and the second pretreatment reactor 22 is connected to the purification reactor 3 via a first control mammoth pump 7 connected to the first The cleaning reactor 3 is connected to the degassing space 4Ί of the purification stage 4 by a second control mammoth pump 9 connected to the second air float valve 10 and is provided with a mammoth pump 11 of excess sludge which is led through the aerobic stabilizer 12 of excess sludge to the sludge 13 located above the second pre-treatment reactor 22. The purification reactor 3 is also provided with a first metallurgical sludge return pump 14, which opens into both pre-treatment reactors 2, a first overflow opening 18 for the overflow. moving the activated sludge foam into the second pre-treatment reactor 22 and the first float switch 35 and the second float switch 36 to allow the operation modes of the apparatus to be switched to either economy or extreme. The purification stage 4 is then equipped with a purified water outlet 15, a disinfectant dispenser 16, a second metallurgical sludge return pump 17 which opens into a first pre-screening reactor 21 and a second through-opening 19 for sludge activation of the activated sludge. .

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All components 2,3 and 4 are connected to a common compressed air source 31, for example a compressor, to which the purified water can be aerated, to which also the air float fittings 8 and 10 and all the mammoth pumps 7, 9, 11, 14 are connected. 17, wherein a first regulating element 32, for example a three-way solenoid valve, is connected to the air circulation circuit to control the flow of purified water and a second regulating element 33, for example a one-way solenoid valve, for controlling the pumping of excess sludge. The main distribution line 321 of the normally open normally open control element 32 is connected in series with the main aerators 301 of the pre-treatment reactors 2 and the purification reactor 3 and simultaneously with the first air float armature 8, the first booster pump 7 and the booster pump 14. Auxiliary aerators 302 of the pre-purification reactors 2 are connected in series to the second branch 322 of the normally closed normally closed control element 32 and the second control booster pump 9 with the second booster sludge pump 17 and the aerobic stabilizer 12 are connected via a second air float armature 10. The second control element 33, connected in parallel to the second air duct branch 322, is then connected in parallel to the first auxiliary aerator 303 of the post-purge stage 4 and the mammoth pump 11 of the excess sludge. The whole device is then equipped with a nicely illustrated control automat, for example a computer connected to a power source.

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In the purification process, the contaminated waste water flows through the inlet 6 through the coarse dirt trap 1 to the first pre-treatment reactor 21, where the first sludge pump 14 returns the first sludge from the purification reactor 3. Partially purified waste water flows to the second pre-treatment reactor 22. wherein the second purge sludge pump 14 and the second portion of the return sludge from the purification reactor 3 are also fed to it through the first booth pump 14, and further purified water is pumped through the first control mammoth pump 7 to the purification reactor 3 for further purification stages. At the same time, the first booster pump 7 creates the first storage space.

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-8 for a possible surge inflow of wastewater from both pre-treatment reactors 2. From the purification reactor 3, after a period of time necessary for settling, for example 20-30 minutes, the purified water is pumped by a second control mammoth pump 9 to the degassing space 41 of the post-purification stage 4. the second control mammoth pump 9 creates a second storage space for the inlet of wastewater from the pre-treatment reactors 2. In the purification stage 4, fine sludge particles are deposited on its walls which are entrained by the auxiliary aerator 303 and subsequently pumped back by the second mammoth pump 17 The purified water then flows from the upper zone of the purification stage 4 through the outlet 15 outside the purification plant to a recipient (not shown), when it is automatically added to it as required. disinfectants. The partially stabilized excess sludge in the automatic mode is discharged from the purification reactor 3 by means of a mammoth pump 11 of the excess sludge through the stabilizer 12 into the sludge bed 13, which can also be realized in the form of a drainage collection bag.

If there is no waste water flowing into the plant within the set time interval, the control unit switches its operation to the energy saving mode, which ensures that the activated sludge is kept in good condition without the need for long-term wastewater inflow and significantly reduces the power consumption for the plant.

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The individual cleaning phases of the intermittent operation of the plant, in which the pre-treatment reactors 2 are under stirring, aeration and possibly settling, and in the cleaning reactor 3, the phases of mixing, aeration, settling, purging of clean water and purging of excess sludge can be described by dependencies resulting from variable activities 31 of the compressed air and the first control element 32 and the second control element 33 connected thereto, by means of the following table:

Phase number . ... A> .. _v . A: J 2 Yo-o 3 4 5 i Α, φίΜίΚ Source 31 interrupt, on on off • in ø -...- 4, -: - on <on element 32 off off off ' on on element 33 off off off off on

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-9 Phase 1 - mixing:

This cleaning phase takes place with intermittent air supply from the compressed air source 31 with the first regulating element 32 open, where this air is supplied to the main aerators 301 of the pre-clarification reactors 2 and the purification reactor 3 and simultaneously through the first air float armature 8 to the first control mammoth pump 7 and to the first metering pump 14 of the return sludge. The second control mammoth pump 9 is disconnected so that no sludge water is pumped from the activation reactor 3.

Phase 2 - aeration:

This cleaning phase proceeds in the same way as the preceding one, except that compressed air is supplied continuously from the source 31.

Phase 3 - settling:

The settling takes place when the compressed air supply from the source 31 is interrupted, when all the aerators 301, 302 and 303 and all the mammoth pumps 7, 9, U, 14 and 17 are inoperative.

and

Stage 4 - pumping of purified water:

This cleaning phase takes place when the first control element 32 is switched to the second position, the secondary aerators 302 in both pre-treatment reactors 2 are actuated, and at the same time the second control booster pump 9 for pumping clean water and the second booster pump are switched on via the second air float armature. The purified water then flows through the effluent 15 from the purification stage 4. After the level in the activation reactor 3 has fallen below a set minimum, the second air float valve 10 closes the air supply to the second control booster pump 9. , thus immediately stop pumping out purified water but

- 10 · · 10 · 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 ················ · · · · · · · The function of other functional elements is running to the end of the selected time interval due to the setting of the parameters of the control automat.

Phase 5 - pumping off excess sludge:

This phase begins at the same time as purging the pumped water at intermittent switching of the second control element 33, depending on its setting in the control automat.

Device power saving mode:

If the level in the purification reactor 3 falls below the minimum set value, the first float switch 35 is switched on and only the aeration and settling or mixing, i.e. the above-described economical purification, takes place in the device for a certain time depending on the setting of the controller. phases 2 and 3, or phase 1. Setting the time intervals for the power saving mode can be done in several levels according to the time of non-flow of new wastewater, for example for 1 hour and 24 hours, and thus the power saving mode can also be performed in several levels.

Operation of the device in the case of a surge inflow of waste water:

In the event of a sewage inflow, when the second control mammoth pump 9 is not sufficient to drain water from the purification reactor 3, the control reactor 3 raises the level above the maximum level set for the second float switch 36, which immediately ensures the device is switched to extreme operation. In this mode, the compressed air source 31 is switched off first, and in all the reactors 21, 22 and 3, the settling phase described above takes place, and after some time the purification water pumping phase described above is also started. Upon completion of this, when the level drops ensure the second float switch 36 is switched over, the controller automatically switches the device to normal operation, in which all the cleaning phases indicated in Tables 1 to 5 are carried out in sequence.

The described embodiment is not the only possible solution according to the invention, but in the case of a plant for higher volumes of purified water, more than two pre-treatment reactors 2 may be used and the device need not be arranged in a common shell 5. The purification stage 4 does not have to be a settling tank but can be realized as a filter and the device need not be equipped with either a disinfectant dispenser 16 or an aerobic stabilizer 12 of excess sludge. In another arrangement of reactors 2 and 3, the aerators 301, 302 and 303 and the mammoth pumps 7, 9, H, 14 and 17 do not have to be connected to a single common source of compressed air 31 or the main and secondary aerators 301 and 302 to the compressed air source 31 separately via the third control element 34, as shown in FIG. In order to prevent clogging of the coarse dirt trap (1), it can also be equipped with another auxiliary aerator (not shown).

Industrial applicability

The method of multi-stage biological waste water treatment with intermittent operation and the device for carrying out this method according to the invention can be used in wastewater treatment plant projects and constructions, especially for sewage from 2 to 1000 connected residents from housing, hotels, boarding houses, restaurants, gas stations stations and smaller industrial enterprises.

Claims (10)

Claims ROΑ PROTECTION 1. A method of multi-stage biological wastewater treatment with intermittent operation in a plant comprising at least two pretreatment reactors, a purification reactor and an internal air recirculation circuit connected to at least one compressed air source, characterized in that depending on selected time intervals or amount of effluent according to pre-set parameters in each of the pre-treatment reactors is controlled independent cleaning process consisting of aeration of purified water and selected combination of cleaning phases consisting of mixing of purified water and sludge settling while ensuring pumping of pre-treated water into the cleaning reactor. cleaning process consisting of mixing and aerating the purified water and sludge settling while ensuring pumping Purification of purified water, recirculation of return sludge back to each or any of the pre-treatment reactors, and occasional pumping of excess sludge away from the plant when initiation or termination of individual stages of the purification process in the pre-purification reactors or purification reactor is initiated float switches. The method of multi-stage biological wastewater treatment according to claim 1, characterized in that, upon stopping the wastewater inflow to the plant, compressed air is supplied intermittently to the main aerators of the pre-treatment reactors and the purification reactor by adjusting the different timing levels. aeration of water without pumping out purified water. 3. The method of claim 1, wherein, when the level in the activation reactor is raised above the maximum level, the supply of pressurized air from the source to the purification reactor or all reactors is stopped first and after a certain period of time necessary to ensure the flow. the settling phase begins the phase of pumping the purified water from the number 4 devices into the regular water with intermittent water - a 13-thawing reactor, after which the mode of operation is switched again, in which all the cleaning phases are carried out successively. 4. A plant for multi-stage biological waste treatment using an activated sludge activated sludge activation system, comprising at least two pre-treatment reactors and a purge reactor connected in series, and an internal compressed air circulation circuit with aerators located in all reactors, characterized in that the interconnected pre-treatment reactors (2) are completely separated from the purification rector (3) with which the last of the pre-treatment reactors (22) is connected by a first control mammoth pump (7) connected to the first air float armature (8) when at the inlet (6) a sewage collector (1) is located in the first pre-treatment reactor (21), the activation reactor (3) being equipped with a second control mammoth pump (9) for pumping clean water connected to the second float control valve (10); mamutko a return sludge pump (14) opening into each of the pre-treatment reactors (2) and a mammoth pump (11) of excess sludge. Apparatus according to claim 4, characterized in that the excess sludge mammoth pump (11) is led through the aerobic excess sludge stabilizer (123) to a sludge tank (13) which is connected to one of the pre-treatment reactors (2) to allow drainage sludge water back into the purification process. Apparatus according to claims 4 and 5, characterized in that it comprises a post-purification stage (4) into which a second control mammoth pump (9) flows and which is provided with a clean water outlet (15) and a second mammoth pump (17). ) a return sludge leading to a first pre-treatment reactor (21). Apparatus according to claims 4 to 6, characterized in that all the mammoth pumps (7, 9, 11, 14, 17) and the aerators (301, 302, 303, 304) of the reactors (2, 3), of the post-purification stage (4). ) and the surge tank stabilizer (12) are provided with a power supply (12). - 14 (31) of the compressed air are connected via a first control element (32) or a second control element (33). Apparatus according to claim 7, characterized in that the main aerators (301) of the reactors (2, 3), the first air float armature (8) and the first air-lift valve are connected to one branch of the circulating air circuit coming from the first control element (32). the return sludge pump (14) and the second branch are connected to the auxiliary aerators (302) of the pre-treatment reactors (2), second to the second float control valve (10), the second booster pump (9) and the second booster pump (17) and a second auxiliary aerator (304) of the excess sludge stabilizer (12), wherein a mammoth pump (11) of the excess sludge is connected to the second control element (33), which is connected in parallel to the second branch of the first control element (32). the auxiliary aerator (303) of the post-purification stage (4). Apparatus according to claims 4 to 8, characterized in that the cleaning reactor (3) is provided with a first through hole (18) for transferring the activated sludge foam to the last pre-treatment reactor (22) and the after-treatment stage (4) is provided with a second through hole (19) for transferring the activated sludge foam to the first pretreatment reactor (2Ί). Device according to Claims 4 to 9, characterized in that the post-blowing stage (4) is equipped with a disinfectant dispenser (16).